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Shot Peening

Shot Peening

Shot peening is a process in which hardened media called “shot” is used to bombard the surface of a metal part. This effectively hammers the part with thousands of small metal balls, which dimple, or “peen” the surface. Why is this necessary? When metal components are manufactured, they go through various hot and cold metal working processes, including rolling, forging, bending, machining, heat treatment, and grinding. These processes leave the surface of the manufactured components in tension. If this tension is not relieved, cracks will tend to form, which can lead to component failure.

A proven and effective way to reduce surface tension, and is used in many industries to extend the life of critical components. Because the overlapping dimples from shot peening leave the surface of a component in compression, rather than in tension, surface cracks are much less likely to form, and the risk of failure due to crack propagation is greatly reduced. The analogy we like to use here in the shop is the tight t-shirt versus a loose t-shirt. Which shirt is more likely to tear, the tight one that barely fits, or the loose one that just hangs? A “loose” surface (a surface in compression) is much less likely to crack than a surface in tension.

Shot peening is an important part of what we do at Weddle Industries. All Weddle Racing gears, ring and pinions, input shafts, heavy duty slider hubs, and many of our other high-end components, are fully shot-peened as part of the manufacturing process. For components that were not originally shot peened (such as stock gears), we have in-house shot peening capability to help make them more suitable for use in high-performance applications. Please call for details.